Pu at Johnston Atoll -Reply

[DAVID HARRISON <DHARRISON@doe.lanl.gov>]

We drummed up 32 55-gal drums of
Pu-contaminated coral sands at JA, 16 of low
activity and 16 of higher activity.  We used
Calcium Fluoride and NaI FIDLERs for field 
detection, and 2 FIDLER stations and
NaI-MCA for activity determination in the
"bunker".  The statistics for the operation were
excellent.  The Team Leader for this op was
David Hunter.  A team member designed and
built the MCA.  You might want to get with
one or both.  Respond to my personal email
for more information.  DPH

DHARRISON@DOE.LANL.GOV
>>> Andrew McEwan
<Andrew@nrl.moh.govt.nz> 06/26/97 04:17pm
>>>


On 26 June David Rynders wrote:

"I am designing a verification survey plan for
contaminated coral at
Johnston Atoll.  We plan to scan the surface to
look for the particles. 
  The question is how, if possible, to conduct
sampling for the tiny particles  that is statistical
defensible.  Has anyone done any work like
this?
     Our idea to determine the maximum number
of allowable particles in the coral is to
back-calculate from an allowable lung dose. 
This will give a starting point for the survey
design.

Thanks in advance

CPT David Rynders"

David

The purpose of the survey is not entirely clear
to me.  If lung doses from  resuspension are
the critical measure, the most direct way to
assess these  would be by air monitoring. 
LLNL (Bill Robison and others) have done 
resuspension measurements at Bikini Atoll and
found very low values in the  E-10 to E-11
range for coral soils.

A resuspension factor of E-10 implies a
surface areal contamination of  around 2xE07
Bq/ sq m to keep within a committed effective
dose limit of 1  mSv/y for full time occupancy.

Another exposure route for consideration is
contamination of a wound,  particularly if the
activity is mostly in active particles.  I have
further  information on this if you wish to
follow it up.

Andrew McEwan

_________________________
Andrew C McEwan PhD
National Radiation Laboratory
PO Box 25-099
Christchurch, New Zealand

Ph 64 3 366 5059
Fax 64 3 366 1156
acmcewan@nrl.moh.govt.nz
________________________